LED RGB 5mm Clear CC (5-Pack)

General purpose RGB common cathode LEDs that have a water clear lens.

DESCRIPTION

These are general purpose 5mm RGB common cathode (CC) LEDs that have a water clear lens.  They come in a 5-pack.

PACKAGE INCLUDES:

• Qty 5 – LED RGB 5 mm common cathode water clear

KEY FEATURES OF LED RGB 5MM CC WATER CLEAR LENS:

• RGB (Red/Green/Blue) LEDs contained in same package
• Common cathode (CC)
• 5mm diameter
• Water clear lens
• 20mA max drive current
• Forward voltage drop of 2.1V red and 2.8V for blue and green

The LED is common cathode (CC) which means that all 3 of the LEDs have their cathodes tied together.  The cathode which is the longest lead is connected to ground and the red, green and blue LED pins should be connected to digital or PWM output pins that will be driven active HIGH to light the LEDs.

Calculating LED Resistor Values

These R/G/B LED pins must have series current limiting resistors to prevent damage to the LED or the MCU that is driving them.

They are logic compatible with a max drive current of 20mA and a typical forward voltage drop of 2.1V for the red and 2.8V for the green and blue LEDs.

At an operating voltage of 5V, series voltage dropping resistors of 150Ω for red and 110Ω for blue and green will provide max brightness or larger resistors of around 220- 470Ω can be used to reduce current at a lower brightness.

OUR EVALUATION RESULTS:

LEDs tend to be fun to play with in general and RGB LEDs are the funnest of all.  With regular LEDs, you can turn them on and off, blink them or pulse them rapidly to change the perceived brightness.  With RGB LEDs, you can also add playing with color blending which allows you to create pretty much any colors of the rainbow.

The minimal way to drive the LED is by using logic levels to drive the Red/Green/Blue LEDs either individually or several together.  Using it this way, you can get 7 possible colors consisting of Red, Green, Blue, Yellow (red and green both on), Purple (red and blue both on), Cyan (blue and green both on) or White (all 3 on).  This may be useful for a basic indicator where you want to be able to show several different states using different colors.

More commonly, RGB LEDs are driven  using the PWM outputs of a MCU.  This allows the brightness of each of the Red/Green/Blue LEDs to be adjusted and therefore it is possible to color mix to get virtually any color you want from the LED.

The example program below uses PWM to show off some of the capability of the RGB LED. First it ramps the brightness of each of the Red, Green and Blue LEDs.  Then it arbitrarily mixes the colors of the three LEDs together.

The LED is wired to pins 6, 5 and 3, but any 3 PWM capable pins can be used.  Be sure to use a current limiting resistor in series with each of the pins.  Refer to the picture for the pin-out of the LED.

LED RGB CC Test Program

/*
RGB LED test

Basic code cycling the colors of an RGB LED. 
*/

int RED_PIN = 6; // select a PWM pin for the red LED
int BLUE_PIN = 5; // select a PWM pin for the blue LED
int GREEN_PIN = 3; // select a PWM pin for the green LED
int val=0;
//===============================================================================
//  Initialization
//===============================================================================
void setup() 
{ 
  pinMode (RED_PIN, OUTPUT);
  pinMode (BLUE_PIN, OUTPUT);
  pinMode (GREEN_PIN, OUTPUT);
}
//===============================================================================
//  Main
//===============================================================================
void loop() 
{
  // Cycle each of the Red / Green / Blue LEDs through their brightness range
  Serial.println ("Testing Red LED");
  for (val = 0; val < 256; val++)
  {
    analogWrite (RED_PIN, val);
    delay(25);
  }
  analogWrite (RED_PIN, 0);
 
  Serial.println ("Testing Green LED");
   for (val = 0; val < 256; val++)
  {
    analogWrite (GREEN_PIN, val);
    delay(25);
  } 
  analogWrite (GREEN_PIN, 0);
  
  Serial.println ("Testing Blue LED");
  for (val = 0; val < 256; val++)
  {
    analogWrite (BLUE_PIN, val);
    delay(25);
  }
  analogWrite (BLUE_PIN, 0);

// Fade Green to Red
 for(int i=0; i<255; i++) {
    analogWrite(RED_PIN, i);
    analogWrite(GREEN_PIN, 255-i);
    analogWrite(BLUE_PIN, 0);
    delay(25);
  }

  // Fade Red to Blue
  for(int i=0; i<255; i++) {
    analogWrite(RED_PIN, 255-i);
    analogWrite(GREEN_PIN, 0);
    analogWrite(BLUE_PIN, i);
    delay(25);
  }

  // Fade from Blue to Green
  for(int i=0; i<255; i++) {
    analogWrite(RED_PIN, 0);
    analogWrite(GREEN_PIN, i);
    analogWrite(BLUE_PIN, 255-i);
    delay(25);
  }
}

Notes: 

1. None

TECHNICAL SPECIFICATIONS